Antenna



511m 14% J. B. ATWOOD ZAQLOI ANTENNA Filed May 4, 1942 3 Sheets$heet 1 ATTORNEY June 4, 194%.

ANTENNA Filed May 4, 1942 J. B. ATWOOD 3 Sheets-Sheet 2 B iarnlll lllllm' ill! 37 6' INVENTOR Jahli BY 7 ZM ATTORNEY vim 00$ Patented June 4, 1946 ANTENNA John B. Atwood, River-head, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application May 4, 1942, Serial No. 441,659

22 Claims. 1

My present invention relates to antennas. The antennas described herein are especially adapted for use on boats and are especially useful for operation with very. short waves such as waves of the order of ten centimeters or 3000 megacycles.

An object of my invention is to provide an antenna system having a variable beam angle in a vertical plane. By mounting such an antenna or a pair of such antennae on board ship, substantially uniform omni-directional characteristics will be secured with relatively large power gain. More specifically, by mounting an antenna employing the principles of my present invention on board ship so that the broader vertical beam angle is at the sides of the ship and the narrower angle in the direction of the length dimension of the ship, it will be found that my improved antenna having variable vertical directivity increases the power gain of the antenna as a whole. This follows because ordinarily a ship rolls more than it pitches and, consequently, my antenna having characteristics such as described and mounted as described will provide the desired omni-directional characteristic despite the usual motion of the ship over rough water.

In one form my invention is carried out by arranging a linear exposed antenna element between a pair of warped metallic surfaces, the angles and areas between which may be made to vary from point to point around the linear antenna. The warped surfaces may be sections or sectors of two cones. These sectors may be formed by passing appropriate planes through the conical metallic surfaces so that the inter sections of the planes and conical surfaces are hyperbolae.

Where the antenna cannot be mounted in such a manner as to provide a 360 degree response in a horizontal plane, two antennas may be provided, one one each side of the ship, each of which has a horizontal pattern of slightly over 180 degrees so as to provide an overlap. In this case the back side of each antenna may be formed of intersecting metallic plane surfaces so as to form a plane septum.

Further in accordance with my present invention, the conical surfaces of my antenna system may be made adjustable in spacing with respect to each other and, further, the generatrix of each surface may be varied in angle with respect to the directrix or axis. of each surface as the generatrix is moved about the axis.

Further description of my present invention will be given in connection with the accompanying drawings wherein:

Figure 1 is a plan view of a cone. Figure 1 also illustrates planes which may be passed through the cone in such a way as to carry out certain features of my invention.

Figurela' is a plan-view of a modification of Figure 1 wherein the cone has a non-circular base. H

Figure 2 is aside view of a conical surface through which two intersecting planes have been passed. The planes are so arranged that the intersections on the surface of the cone are in tersecting hyperbolae. j N Figure 3 is a front elevational view of one form of my antenna system having a horizontal pat, tern of slightly over degrees.

Figure 4 is a side view of Figure 3. i I Figure 5 is a curve showing the horizontal directivity of the septate bi-conical horn of Figures 3 and 4.

Figure 6 is a curved showing the vertical directivity at the center of the septate bi-conical horn of Figures 3 and 4. Figure '7 illustrates an antenna system in accordance with my present invention providing; a 360 degree response in a horizontal plane assum: ing that the axis of the system is arranged Ver tically. 1

As indicated, Figure 1 is a plan view of a cone having a circular base 2 and an apex 4. Assuming the cone to be a metallic surface, I usea sector of this metallic surface, in one form of my invention, lying between the intersecting pairs of planes 68, 8 l0 and l2--l4, l4l6. The resulting metallic conical surfaces are mountedone above the other as at It, 2|] as shown in Figure '7 and provided with an exposed linear antenna element 22 therebetween. Antenna 22 may be connected so as to form the internal conductor of a concentric transmission line, the outer conductor for which is indicated at 24. Both conductors 22 and 24 may then be connected to a transmitter or'receiver (not shown) as desired. As shown in Figure '7, the intersection of 6-8 and 8-H) with the conical surface forms the intersecting hyperbolas 26, 28, 30 and 32. Similarly, the intersecting plane surfaces 'l2- I4 and [4-16 form the hyperbolas 34, 3B, 38, 40 of Figure '7. Antenna radiator or pickup unit 22 may be terminated by an impedance matching device, a will be explained more fully in connection with the modification shown in Figures 3 and 4.

Figure 2 has been given to illustrate more clearly the intersection of plane l2-I4, l 4-16 with one of the conical surfaces of the cone of Figure 1. The intersecting hyperbolas are illustrated at 38, 40 and the intersection of the two planes is indicated by the dotted line l4, l4.

.The antenna system of Figure 7 having the metallic conical surfaces I8, 20 and the linear metallic radiator or pickup unit 22 will be found especially useful on shipboard. It will be found that by making the system as outlined, the vertical directivity in the plane of the drawing of Figure 6 will be much sharper than the vertical directivity or beam angle in a, plane perpendicue lar to Figure 6 and passing through conductor 22. By arranging such an antenna on top of a mast on board a ship so that the sharper characteristic lies along the line of the length of the ship, then the broader characteristic of the antenna in the, perpendicular plane will take care of the rolling of the ship, whereas the sharper characteristic may be used in the other direction since the pitching of the ship .is'no't as great as the rolling. The overall effect is an omnidirectional antenna in a horizontal plane with, however, an overall improved power gain.

Assuming the axis or directrix of the conical surfaces to lie in a line through point 4 and perpendicular to Figure 1 or, in other words, to be coincident with conductr'22, it shoul be clear that the conical surfaces need not be generated by a generatrix making a constant angle with the axis, but rather the generatrix may be made variable in angle with respect to the axis so that the base 2 of Figure 1 might become, for example, an ellipse, such as shown at 2' in Figure 1a. The intersecting planes defining the base edges of the antenna bear the same reference numerals as in Figure 1, since their form, placement, and function are the same as described with reference to Figure 1. Also, the two surfaces I8, 20 of Figure 7 maybe mounted so as to be spatially adjustable with respect to each other.

In case the antennacannot be mounted in such a manner as to provide a 360 degree response in the horizontal plane, two antennas may be provided one on each side of the ship, each of which has a horizontal pattern of slightly over 180 degrees so as to provide an overlap. Such an antenna arrangement having an omnidirectional horizontal pattern over a range slightly over 180 degrees is illustrated in Figures 3 and 4. The Warped or conical surfaces 50, 52 are formed as shown in Figure l by passing pairs of planes l2-I4, I l-l6 and 54-56, '6-58 through the conical metallic surfaces which are to form part of the antenna arrangement. As before, the base 2 of the cone, while preferably circular, may be elliptical in shape, in which case the generatrix of the metallic conical surfaces will make a variable angle with the axis represented by the'transmission line conductor 22. With the base of the cone circular, the intersections 60,1?2, M, 66 will be hyperbolae and for practical reasons the points 68, formed by their intersection may be rounded off as desired. Also, the intersecting planes 54-56, 56-58 may be made of metal and used as part 'of the system as shown in Figures '3 and 4. The two intersecting planes form a metallic septum 12, 7-4 intersectingalong the line 16, as shown in Figure 3. The two antenna elements or surfaces 50, 52 may be soldered to or otherwise affixed to the metal reflecting surfaces 72, 7 Preferably, however, the surfaces re made "spatially adjustable with respect to each other. This may -be accomplished, for example, as illustrated in Figure 3 by providing the partitions orthe septa T2, T4 with slots'80, 82 and one of the surfaces (or both if desired) with upstanding :edges or flanges 84, 8'6. The position of the surfaces may then be adjusted by means of bolts, nuts and washers '88, 90 passing through suitable-openings int-he flanges and slots 80, 82.

The transmission line 'may exten'd beyond the lower surface 52 as illustrated at 12A and 24A. A short-circuiting disc 25 maybe provided, movable by means of a handle 2'! whereby'the impedance of conductor22 may be suitably matched or otherwise adjusted.

I have found when operating a system such as shown Figures 3 and 4 at a wave length of ten centimeters the distance between the septum 16 and the conductor 22 may be, for good operation, an odd number, including one, of quarter wave lengths. Also' at this frequency of operation typical dimensions of the apparatus actually set up were approximately as follows: The distance from A to B the longest dimension of the surface-fifteen inches; the distance from C to D (see Figure 4)approximately seven inches; the angle between the conical surfaces-45 degrees; the distance across points E and F-approximately three inches; the distance between the apices of the conical surfaces, that is to say, the length of the exposed portion of conductor 22-approximately a quarter Wave length.

As before explained in connection with the system of Figures 3 and 4, the angle between the surfaces may continuously vary. That is, the angle may vary continuously from 45 degrees for the angle AA to 20 degrees for BB. Simultaneously with a change in angle the lengths of the sides of the surfaces may be varied.

The length dimension of each truncated conical surface, as measured from the apex along a generatrix and in a direction parallel to or away from the metal partitions forming the septum, should not be less than one wave .length long where the wave length taken is, of course, that of the radiated or received waves. Also, the metal planes or partitions forming the septum are shown in Figures 1, 3 and 4 to make an angle with each other slightly greater than degrees where the angle is measured between the surfaces of the partitions on which the conical elements are supported. This angle maybe made greater, equal to or smaller than 180 degrees as desired. 7

Having thus described my invention what I claim is: V

1. An antenna element comprising a sector of a conical metallic surface, said sector .being formed by passing a pair of intersecting plane surfaces through said conical surface,-said plane surfaces intersecting 'in a line parallel to and displaced from the axis of said conical metallic surface.

2. An antenna element comprising a .curved metallic surface in the form of a surface of revolution having as a limiting boundary the ,intersection of a pair of planesurfaces with saidcurved surface, said plane surfaces intersecting .in a line parallel to and displaced from the principal axis of said curved metallic surface.

3. An antenna element comprising ,a conical metallic surface and a plane metallic surface said plane metallic surface intersecting said conical surface and being parallel to and substantially displaced from the axis of said conical surface.

4. An antenna :element comprising a conical metallic surface and a pair of intersecting plane metallic surfaces, said intersecting ,plane surfaces also intersecting said conical surface, the line of intersection of .said planeusurfaces being -parallel 'to the principal axis of .said conical surface and displaced -from said axis .byan odd number of quarter wave lengths of the operating wave length.

5. An antenna element in the form :of a sector of a metallic conical surface, said surface being generated by a generatrix making a variable angle with the axis or directrix of said surface and the extent of said sector 'being defined by .the intersection of said "conical surface with a number of planes having elements parallel to the axis of said cone, at least a pair of said planes intersecting at a distance from said axis.

6. An antenna arrangement comprising a pair of conical metallic-surfaces and a pair of plane metallic surfaces, said plane surfaces intersecting said conical surfaces, said plane surfaces intersecting each other in a straight line parallel to and displaced from the axis of said conical surfaces.

I 7. Apparatus as claimed in claim 6, characterized by the fact that said conical surfaces are spatially adjustable with respect to each other.

8. Apparatus as claimed in claim 6 characterized by the fact that the generatrix of each conical surface makes a variable angle with the directrix of the conical surfaces.

9. An antenna arrangement comprising a pair of conical metallic surfaces, a linear antenna element lying exposed between the apices of said surfaces, and a pair of plane metallic surfaces angularly disposed with respect to each other and intersecting each other and intersecting said conical surfaces, the intersection of the planes being a straight line parallel to and displaced from said linear antenna element.

10. Apparatus as claimed in claim 9, characterized by the fact that said conical surfaces are further sectored by another pair of intersecting planes making a different angle than said firstmentioned pair of intersecting plane metallic surfaces.

11. An antenna arrangement comprising a pair of sectors of conical metallic surfaces, each of said conical surfaces arranged so as to have their axes superimposed, each of said sectors being formed by passing a pair of intersecting plane surfaces through both of said conical surfaces, said plane surfaces intersecting in a line parallel to and displaced from the common axis of said conical surfaces.

12. An antenna arrangement comprising a pair of sectors from a pair of conical metallic surfaces having a common axis, said sectors being formed by so passing a pair of intersecting plane surfaces through said conical surfaces that the intersections of the intersecting plane surfaces with each conical surface are intersecting hyperbolae.

13. An antenna arrangement comprising a pair of conical metallic surfaces having a common axis and a pair of intersecting plane metallic surfaces, said intersecting plane surfaces intersecting said conical metallic surfaces, said intersecting plane surfaces being further characterized by the fact that they intersect each other in a straight line which is parallel to the common axis of said conical surfaces and displaced therefrom by an odd number of quarter wave lengths taken at the operating frequency.

14. An antenna arrangement comprising a pair of conical metallic surfaces arranged along a common axis, each of said conical surfaces having its shape further fixed by the intersection therewith of two pairs of intersecting plane surfaces, the lines of intersection of said plane surfaces being parallel to and displaced from the common axis along which said conical surfaces are arranged.

15. An antenna arrangement comprising a pair of sectors of conical metallic surfaces, each of said conical surfaces arranged so as to have their axes superimposed, each of said sectors being formed by passing a pair of intersecting plane surfaces through both of said conical surfaces, said plane surfaces intersecting in a line parallel to and displaced from the common axis of said conical surfaces, means for supporting said conical surfaces in displaced relation along said axis, and means for permitting adjustment of the separation between said conical surfaces.

16. An antenna arrangement comprising a pair of sectors from a pair of conical metallic surfaces having a common axis, said sectors being formed by so passing a pair of intersecting plane surfaces through said conical surfaces that the intersections of the intersecting plane surfaces with each conical surface are intersecting hyperbolae, means for supporting said metallic sectors in spaced relation along their common axis, and means for varying the spacing of said sectors in a direction'along said common axis.

17. An antenna arrangement comprising a pair of conical metallic surfaces having a common axis and a pair of intersecting plane metallic surfaces, said intersecting plane surfaces intersecting said conical metallic surfaces, said intersecting plane surfaces being further characterized by the fact that they intersect each other in a straight line which is parallel to the common axis of said conical surfaces and displaced therefrom by an odd number of quarter wave lengths taken at the operating frequency, and means for adjustably supporting said conical surfaces in spaced relation with respect to each other.

18. An antenna arrangement comprising a pair of conical metallic surfaces arranged along a common axis, each of said conical surfaces having its shape further fixed by the intersection therewith of two pairs of intersecting plane surfaces, the lines of intersection of said plane surfaces being parallel to and displaced from the common axis along which said conical surfaces are arranged, and means for adjustably supporting said conical surfaces in spaced relation with respect to each other.

19. An antenna element including a conductive body having a surface in the form of a portion of a cone, the extent of said conical'surface being defined by the intersection of said cone with at least a pair of intersecting planes parallel to but spaced from the axis of said cone.

20. An antenna element including a conductive body having a surface in the form of a portion of a cone, the extent of said conical surface being defined by the intersection of said cone with a number of planes having elements parallel to the axis of said cone, at least a pair of said planes intersecting at a distance from said axis.

21. An antenna element including a sector of a conical metallic surface, said sector being defined by passing a number of planes through said conical surface, said planes having elements parallel with the axis of said surface, and at least a pair of said planes intersecting at a distance from said axis.

' 22. An antenna element including a sector of a conical metallic surface, said sector being defined by passing a number of planes through said conical surface, said planes having elements parallel with the axis of said surface, and at least a pair of said planes intersecting at a distance from said axis, said conical surface being generated by a generatrix making a variable angle with the axis of said surface.

JOHN B. A'IWOOD. 

